This invention relates generally to yarn cores or tubes, and more particularly, to the pickup or start-up grooves provided therein.
The term "yarn" is used very broadly in the textile industry to describe long strings of fiber materials, such as Nylon, cotton, fiberglass, polyester, etc. These strings (yarn) are wound on tubes, cones, or the like, as a means for facilitating carrying the yarn from one textile process to another. The fully wound tubes are normally referred to as "yarn packages".
In the forming of a yarn package, the tube is placed on a yarn winder spindle which effects high speed rotation of the tube. As the yarn proceeds to the winder and is ready to be wound onto a tube, provision must be made for adhering the leading end of the yarn to the tube. This adherence is normally accomplished by means of a thin slit or groove in the tube surface which, through a wedging action, grips the leading portion of the yarn as it is moved over the groove in the rapidly rotating tube. This action of the groove in gripping the yarn is referred to as a "pickup".
After pickup, the tube continues its high speed rotation with the yarn wrapping therearound in multiple layers which extend along the length of the tube. Wrapping of the yarn in layers along the length of the tube is effected basically by a tube traversing mechanism which guides the yarn back and forth along the length of the rotating tube.
After winding a few layers about the tube, the gripping of the end section of the yarn by the groove is no longer required for the tube winding operation itself in that the initial few wraps of yarn provide a sufficient holding force for an effective continuation of the yarn winding operation. However, it is desirable that the groove effectively retain this leading end section of the yarn in that this end needs to be accessible for interconnection to the leading end of a following yarn package in subsequent operations wherein the yarn is fed from successive yarn packages in a continuous manner.
Heretofore, yarn pickup grooves have been designed to pick up a very limited denier range of yarn. In an attempt to increase the range of yarn sizes which can be accommodated by a particular groove, grooves with a wide lead-in section were devised. While such grooves have found wide commercial acceptance, they have one significant drawback in particular, the inability to pick up the yarn in both directions of rotation. Thus, depending on the direction of pickup which can be accommodated, the improved grooves are often referred to as right hand grooves or left hand grooves. The U.S. patent to J. M. Heatherly, No. 3,103,305, issued Sept. 10, 1963, refers to a typical single direction tube and specifically a tube with a right hand groove therein. Basically, looking from the left hand or ungrooved end of the tube in FIG. 1 of Heatherly, the wide section of the groove, that initially receiving the yarn for subsequent gripping within the narrow section, is to the right, thus requiring positioning of the tube on the spindle for rotation toward the right or clockwise, in conjunction with an introduction of the yarn, normally from the right side, in a manner so as to initially engage the wide section of the groove for a full, smooth reception therein and subsequent gripping engagement within the following narrow section.
In the actual winding operation, the empty tubes are normally placed in pairs on a winder spindle with the grooved ends of the tubes adjacent each other. This general arrangement, noted in the "prior art" illustration of FIG. 1, provides a convenient means for winding the yarn on two tubes simultaneously. Such an arrangement, as will be appreciated from FIG. 1, has heretofore required the adjacent ends of the two tubes to have, respectively, a left hand groove and a right hand groove.
The requirement for tubes with left hand grooves and tubes with right hand grooves gives rise to obvious inventory problems. In addition, there is a specific need to insure that the tubes have been properly oriented on the spindle for sequential pickup of the yarn on the two tubes.
In some instances, it has been proposed to provide similar grooves adjacent the opposite ends of each tube, providing in effect, a right hand groove at one end and a left hand groove at the other end. While such an arrangement would eliminate the necessity of stocking two different types of tubes, additional expense would be involved in the forming of two separate cuts or grooves in a single tube. Further, the problem of a proper orientation of the tubes on the spindles would still exist.